Move cc.imageMutator into the android package

Prepare for making the image mutator available to all modules and
moving it between the os and arch mutators by moving it into the
android package and using an interface implemented by the module
types to control it.

Bug: 142286466
Test: No unexpected changes to out/soong/build.ninja
Change-Id: I0dcc9c7b5ec80edffade340c367f6ae4da34151b